The present invention relates to document-handling apparatus and more particularly to a stream feed detector for such apparatus.
In many types of document handling apparatus, such as automatic mailing machines, documents are routed in succession or in seriatim through the apparatus wherein one or more operations are performed on each document. For example, in an automatic mailing machine, envelopes may be automatically weighted, sealed and imprinted with the proper amount of postage before being delivered to a stacker deck from which they will eventually be removed by an operator. Since each of the several operations can be performed on only one envelope at a time, a minimum separation between successive envelopes must be maintained to minimize the risk of jams or operation errors; e.g., the weighing of two envelopes as a single envelope. Failure to maintain the minimum separation is a condition generally referred to as stream feeding.
While stream feeding might be avoided by greatly increasing the intervals between feeding of individual envelopes, this unavoidably reduces the throughput of the apparatus and eliminates one of its primary advantages.